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Mazda CX 7. Manual - part 41

ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–119

01-02

End Of Sie

DTC P0301, P0302, P0303, P0304[L3 WITH TC]

id010239806600

INSPECT FUEL PRESSURE (LOW-SIDE)

• Connect the fuel pressure gauge between the

fuel pump and the high pressure fuel pump.

• Measure the low side fuel pressure.

(See01-14-5 FUEL LINE PRESSURE
INSPECTION[L3 WITH TC].)

• Is the low side fuel pressure within the

specification?

Yes

Go to the next step.

Inspect for the following.

• Fuel line restriction

• Fuel filter clogging

If normal replace the fuel pump.Then go to Step 26.

INSPECT SEALING OF ENGINE COOLANT
PASSAGE

• Perform “ENGINE COOLANT LEAKAGE

INSPECTION.”
(See01-12-6 ENGINE COOLANT LEAKAGE
INSPECTION[L3 WITH TC].)

• Is there any malfunction?

Yes

Repair or replace the malfunctioning part according to the
inspection results.
Then go to the next step.

Go to the next step.

VERIFY TROUBLESHOOTING OF MISFIRE DTC
COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Turn the ignition switch to the ON position

(Engine off).

• Clear the DTC from the memory using the M-

MDS.

• Perform the HO2S heater, HO2S, and TWC

Repair Verification Drive Mode.
(See01-02-10 OBD-II DRIVE MODE[L3 WITH
TC].)

• Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.
(See01-40-6 PCM REMOVAL/INSTALLATION[L3 WITH
TC].)

Go to the next step.

VERIFY AFTER REPAIR PROCEDURE

• Perform the “AFTER REPAIR PROCEDURE”.

(See01-02-10 AFTER REPAIR
PROCEDURE[L3 WITH TC].)

• Are any DTCs present?

Yes

Go to the applicable DTC troubleshooting.
(See01-02-13 DTC TABLE[L3 WITH TC].)

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0301
DTC P0302
DTC P0303
DTC P0304

Cylinder No.1 misfire detected
Cylinder No.2 misfire detected
Cylinder No.3 misfire detected
Cylinder No.4 misfire detected

DETECTION

CONDITION

• The PCM monitors the CKP sensor input signal interval time. The PCM calculates the change of interval

time for each cylinder. If the change of interval time exceeds the preprogrammed criteria, the PCM detects
a misfire in the corresponding cylinder. While the engine is running, the PCM counts the number of misfires
that occurred at 200 crankshaft revolutions and 1,000 crankshaft revolutions and calculates a misfire
ratio for each crankshaft revolution. If the ratio exceeds the preprogrammed criteria, the PCM determines
that a misfire, which can damage the catalytic converter or affect emission performance, has occurred.

Diagnostic support note

• This is a continuous monitor (Misfire).

• The MIL illuminates if the PCM detects a misfire which affects emission performance in two consecutive

drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.

• The MIL flashes if the PCM detects a misfire which can damage the catalytic converter during the first drive

cycle.

• PENDING CODE is available if the PCM detects a misfire which affects emission performance during first

drive cycle.

• FREEZE FRAME DATA is available.

• DTCs are stored in the PCM memory.

POSSIBLE

CAUSE

• Spark plug malfunction

• Ignition coil malfunction

• Ignition system malfunction

• Fuel injector malfunction

• Air suction in intake air system (between dynamic chamber and cylinder head)

• Inadequate engine compression due to engine internal malfunction

• Related connector or terminal malfunction

• Related wiring harness

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–120

Diagnostic procedure

STEP

INSPECTION

ACTION

VERIFY FREEZE FRAME DATA AND
DIAGNOSTIC MONITORING TEST RESULTS
HAVE BEEN RECORDED

• Have the FREEZE FRAME DATA and

DIAGNOSTIC MONITORING TEST RESULTS
(Misfire related) been recorded?

Yes

Go to the next step.

Record the FREEZE FRAME DATA and DIAGNOSTIC
MONITORING TEST RESULTS on the repair order, then
go to the next step.

VERIFY RELATED REPAIR INFORMATION
AVAILABILITY

• Verify related Service Bulletins and/or on-line

repair information availability.

• Is any related repair information available?

Yes

Perform repair or diagnosis according to the available
repair information.

• If the vehicle is not repaired, go to the next step.

Go to the next step.

VERIFY RELATED PENDING CODE OR
STORED DTCs

• Turn the ignition switch off then to the ON

position (Engine off).

• Verify related pending code or stored DTCs.

• Are other DTCs present?

Yes

Go to the appropriate DTC troubleshooting.
(See01-02-13 DTC TABLE[L3 WITH TC].)

Go to the next step.

VERIFY CURRENT INPUT SIGNAL STATUS
(KEY TO ON /IDLE)

• Access APP1, APP2, ECT, IAT, MAF, RPM, TP

and VSS PIDs using the M-MDS.
(See01-40-6 PCM INSPECTION[L3 WITH
TC].)

• Is there any signal that is far out of specification

when the ignition switch is turned to the ON
position and the engine idles?

Yes

Inspect the suspected circuit and/or part according to
inspection results. Then go to Step 14.
(See01-40-6 PCM INSPECTION[L3 WITH TC].)

Go to the next step.

VERIFY CURRENT INPUT SIGNAL STATUS
UNDER TROUBLE CONDITION

• Inspect the same PIDs as in Step 4 while

simulating the FREEZE FRAME DATA
condition.

• Is there any signal which causes drastic

changes?

Yes

Inspect the suspected circuit and/or part according to
inspection results. Then go to Step 14.
(See01-40-6 PCM INSPECTION[L3 WITH TC].)

Go to the next step.

INSPECT SPARK PLUG CONDITION

• Turn the ignition switch off.

• Remove the spark plug from the suspected

cylinder.

• Inspect the spark plug condition:

— Cracks

— Excess wear

— Gap

— Wetness

• Is there any problem found on the spark plug?

Yes

• If a spark plug is wet, fuel flooding is suspected. Then

go to Step 14.

• If a spark plug has cracks, excessive wear or an

improper gap, replace the malfunctioning spark plug.
Then go to Step 14.

Go to the next step.

INSPECT INTAKE-AIR SYSTEM FOR AIR
SUCTION

• Inspect for air leakage at the following:

— Around connection of dynamic chamber and

intake manifold

— Around connection of intake manifold and

cylinder head

• Is air leakage found?

Yes

Repair or replace suspected part, then go to Step 14.

Go to the next step.

INSPECT SEALING OF ENGINE COOLANT
PASSAGE

• Perform “ENGINE COOLANT LEAKAGE

INSPECTION.”
(See01-12-6 ENGINE COOLANT LEAKAGE
INSPECTION[L3 WITH TC].)

• Is there any malfunction?

Yes

Repair or replace the malfunctioning part according to the
inspection results.
Then go to Step 14.

Go to the next step.

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–121

01-02

End Of Sie

INSPECT FUEL INJECTOR WIRING HARNESS

• Remove the intake air system parts.

• Disconnect the fuel injector connector on

suspected cylinder.

• Connect the NOID LIGHT to the fuel injector

terminals.

• Inspect the light dim during cranking.

• Does the light not illuminate?

Yes

Go to the next step.

Inspect the fuel injector wiring harnesses.
Repair or replace if necessary, then go to Step 14.

INSPECT IGNITION COIL HARNESSES

• Inspect the ignition coil related wiring harness

condition (intermittent open or short circuit) of
the suspected cylinder.

• Are the wiring harness conditions normal?

Yes

Go to the next step.

Repair the suspected wiring harnesses, then go to Step 14.

INSPECT IGNITION SYSTEM OPERATION

• Carry out the spark test.

(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC])

• Is a strong blue spark visible at the suspected

cylinder?

Yes

Go to the next step.

Repair or replace the malfunctioning part according to the
spark test result.
Then go to Step 14.

INSPECT ENGINE COMPRESSION

• Inspect the engine compression.

(See01-10-9 COMPRESSION
INSPECTION[L3 WITH TC].)

• Is the engine compression normal?

Yes

Go to the next step.

Overhaul the engine, then go to the next step.

INSPECT FUEL INJECTOR OPERATION

• Connect the M-MDS to DLC-2.

• Access INJ#1, INJ#2, INJ#3, INJ#4 PIDs.

• Start the engine and warm it up to the normal

operating temperature.

• Turn the fuel injector off from on using the PID

simulation function.

• Does the engine speed decrease while the fuel

injectors are turned off?

Yes

Go to Step 14.

Go to the next step.

VERIFY IF TROUBLESHOOTING OF MISFIRE
DTC COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Start the engine.

• Clear the DTC from the PCM memory using

the M-MDS.

• Perform the HO2S heater, HO2S, and TWC

Repair Verification Drive Mode. (See01-02-10
OBD-II DRIVE MODE[L3 WITH TC].)

• Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.
(See01-40-6 PCM REMOVAL/INSTALLATION[L3 WITH
TC].)

Go to the next step.

VERIFY AFTER REPAIR PROCEDURE

• Perform the “AFTER REPAIR PROCEDURE”.

(See01-02-10 AFTER REPAIR
PROCEDURE[L3 WITH TC].)

• Are any DTCs present?

Yes

Go to the applicable DTC troubleshooting.
(See01-02-13 DTC TABLE[L3 WITH TC].)

Troubleshooting completed.

STEP

INSPECTION

ACTION

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–122

DTC P0327[L3 WITH TC]

id010239806700

Diagnostic procedure

DTC P0327

Knock sensor circuit low input

DETECTION

CONDITION

• PCM monitors the input signal from the knock sensor when the engine is running. If the input voltage at the

PCM terminals between 2V and 2U is below 0.12 V, the PCM determines that the knock sensor circuit has
a malfunction.

Diagnostic support note

• This is a continuous monitor (CCM).

• MIL illuminates if the PCM detects the above malfunction condition during the first drive cycle.

• FREEZE FRAME DATA is available.

• DTCs are stored in the PCM memory.

POSSIBLE

CAUSE

• Knock sensor malfunction

• Connector or terminal malfunction

• Open or short to ground circuit between knock sensor connector terminal A and PCM terminal 2U

• Open or short to ground circuit between knock sensor connector terminal B and PCM terminal 2V

• Knock sensor wires (2) shorted

• PCM malfunction

STEP

INSPECTION

ACTION

VERIFY FREEZE FRAME DATA HAS BEEN
RECORDED

• Has the FREEZE FRAME DATA been

recorded?

Yes

Go to the next step.

Record FREEZE FRAME DATA on the repair order, then go
to the next step.

VERIFY RELATED REPAIR INFORMATION
AVAILABILITY

• Check for related Service Bulletins and/or on-

line repair information availability.

• Is any related repair information available?

Yes

Perform the repair or diagnosis according to the available
repair information.

• If the vehicle is not repaired, go to the next step.

Go to the next step.

INSPECT KNOCK SENSOR CONNECTOR
TERMINAL FOR POOR CONNECTION

• Turn the ignition switch off.

• Disconnect the knock sensor connector.

• Check for poor connection at terminals A and B

(such as damaged, pulled-out pins, corrosion).

• Is there any malfunction?

Yes

Repair the terminal, then go to Step 9.

Go to the next step.

PCM

KNOCK SENSOR

WIRING HARNESS SIDE CONNECTOR

KNOCK SENSOR

5 6

PCM

WIRING HARNESS SIDE CONNECTOR

2BE 2BA 2AW 2AS 2AO 2AK 2AG 2AC 2Y 2U 2Q 2M

2BH 2BD 2AZ 2AV 2AR 2AN 2AJ 2AF 2AB 2X 2T 2P

2BG 2BC 2AY 2AU 2AQ 2AM 2AI 2AE 2AA 2W 2S 2O

2BF 2BB 2AX 2AT 2AP 2AL 2AH 2AD 2Z

2V 2R 2N

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